Manufacture of amines



Patente d May 16, 1944 MANUFACTURE OF AMINES Roland H. Goshorn, Trenton, illicit, assignor to' Sharples Chemicals Inc., Philadelphia, Pa., a corporationof Delaware No Drawing. Original application September 26,

UNITED STATES PATENT OFFICE 1940, Serial No. 358,426. Divided and this application April 2, 1942, Serial No. 437,355

4 Claims. (Cl. 260-535) of these functions have been disclosed in the prior art, including silica, alumina, alumina on The present invention pertains to the manufacture of amines. This application is a division of my prior application; Serial No. 358,426, flled In actual practice, the reactions of the three equations given above occur substantially simultaneously, with the result that a mixture of mono-, diand tri-alkyl amines is formed. It is frequently desirable that the reaction be conducted in such a manner as to favor the formation of the mono-alkyl amine and depress the formation of the diand tri-alkyl amines, and

a principal feature of the present invention con-,

sists in the fact that it provides a process by which aproduct predominating in the monoalkyl amine may be obtained. While undesired poly-alkyl amines may be converted into monoalkyl amines or recycled to retard formation of further poly-alkyl amines according to the law of mass action, it is desirable that such treatment be minimized by forming an initial reaction mixture in which the mono-alkyl amine is favored if it is the product desired, and this the present invention accomplishes.

A large number of catalysts havebeen proposed for use in the practice of processes by which ammonia is alkylated to produce alkyl amines in the general manner indicated by the above equations, by vapor phase reaction with alcohols or ethers. Regardless of the catalyst chosen, the practice of the reaction results in the formation of substantial quantities of bysilica, various clays, nickel on pumice, etc. These catalysts have been employed by applicant in many experiments, but none of them is closely comparable to the catalysts of the present invention in favoring formation of mono-alkyl amines.

Another difilculty encountered in the practice of processes of this character consists in the fact that only a small proportion of the mate,- rials passed over the catalyst react to form amines. An object of the present invention has accordingly been to provide catalysts which givev excellent conversions of the raw materials into amines by accelerating the rate of reaction between the allcvlating agent and ammonia, at the same time that they favor formation of the mono-alkyl amines.

Still further objects of the invention will be evident from a reading of the following detailed specification.

In the practice. of the invention, the alkylating agent, which may be either an alcohol or an ether, is passed, together with ammonia or an amine, over a catalyst which consists of a supporting material consisting of granular alumina, this supporting material being coated or impregnated with a compound which is a catalyst in'the practice of hydrogenating and dehydrogenating reactions, and which is chosen from the class consisting of the oxides of nickel, cobalt and chromium.

The supporting catalyst may consist of aluminum oxide in the form of granules, pellets or lumps and is coated with a hydrogenating and dehydrogenating catalyst which is preferably nickel oxide or chromic oxide. These catalysts have been found tobe superior from the standpoint of conversion and yield, inthe manufacture of mono-alkyl amines by reaction of ammonia with alcohols and others, to any catalyst described in the chemical literature.

In the preferred practice of the invention, the ammonia and alkylating agent are passed in vapor phase through a conduit containing the catalyst of the invention, these raw materials be! ing heated to a temperature between 300 and 400 C. durin passage through the conduit. Temperatures somewhat lower than 300 C. and somewhat higher than 400 C. may be employed, but best results are generally obtained within the range between 300 and 400 C.

In the preparation of the catalysts of the invention, the supporting catalyst may be impregnated with a salt of the metallic element of the activating catalyst or promoter. Water may then be' evaporated from the resulting product, and the product resulting from this treatment may then be further treated to efiect decomposition of the salt and formation of the metal oxide. Thus, in the manufacture of a catalyst consisting of alumina impregnated with chromic oxide. alumina is first impregnated with a chromium nitrate solution. The water is then evaporated from the impregnated product under vacuum, and the resulting coated aluminum particles are then put in the reaction tube in which they are later tobe used in the practice of the amination reaction. They are heated in this tube to a temperature of approximately 400 (.7. in order to decompose the chromium nitrate, forming chromic oxide and oxides of nitrogen. These oxides of nitrogen, being volatile, are driven oil, leaving the alumina. coated with the chromic oxide promoting catalyst. At the conclusion of these operations, the alkylating agent, which may, for example, be methyl, ethyl, propyl. butyl, amyl, etc. alcohol or ether. is passed, together with a meleeular excess of ammonia over the resulting composite catalyst, while the conduit containing the catalyst is heated to a temperature sufficient to cause heating of the gases passed through the mixture to the desired reaction temperature.

' The following examples indicate the great superiority of the catalysts of the present invention over those of the prior art in favoring production of mono-alkyl amines. Comparison of-thcse examples with examples of my concurrent application Serial No. 437,356, which is, in a sense, complementary to this application in that it favors formation of poly-alkyl amines, will illustrate the extent to which the processes of these two applications promote formation of the respective desired type of amine as contrasted with the less desired typ Example I this solution. the vacuum was released and the mixtm'e was allowed-to stand over night. The excess water was then evaporated by heating under vacuum. on water bath, with occasional shakinz. The resulting dry material was heated to a temperature of 400' C. in order to eifect decomposition of the chromium nitrate to chromium oxide as an impregnatin and activating catalyst on the alumina. and removal of the oxides of nitrogen formed by decomposition of the chromium nitrate. The resulting catalyst was placed in a glass tube, and a vaporized mixture and butyl alcohol in the .ratio' 'of 3.88 inches of ammonia to each mole of butyl alcohol was passed over-the cataiyst at am velocity of 1000 and anaverage of :49? 'c.. to eifect alkylation or the ammonia. Updn analysis of the reaction can. to produce Tdi-butyl amine, making a mm of scam conversions! alcohol to amine. The mm r the amines obtained in the amine and 17.5% iii-butyl amine based upon the alcohol, making a total yield of 67.8%.

Example II A catalyst consisting of chromic oxide deposited upon activated alumina was prepared in the same manner as discussed in Example I. above. A vaporized mixture of ammonia and butyl alcohol in the ratio of 3.82 moles of ammonia to each mole of butyl alcohol was passed over the catalyst at a space velocity of 1070 and an average temperature of 347 C. to effect alkylation of the ammonia. Upon analysis of the reaction mixture passing from the tube, it was found that 31.8% of the alcohol had reached with the ammonia to produce mono-butyl amine and 11.9% to produce di-butyl amine;

making a total of 43.7% conversion of alcohol to amine. The yield of the desired amine obtained in the practice of the process was 53.1% monobutyl amine and 19.8% oi'di-butyl amine, making a total yield of 72.9%.

Example II! A catalyst consisting of nickel oxide on alumina was prepared by precipitation of nickel nitrate on alumina and treatment of the resulting product in the same manner discussed in Example I in connection with the manufacture of the chromic oxide on alumina catalyst. A vapor phase mixture of butyl alcohol and ammonia containing 3.97 moles of ammonia to each mole of butyl alcohol was passed over the catalyst at a space velocity of 1060 and an average temperature of 350" C. Upon analysis of nickel oxide precipitated on alumina. The conversion of the alcohol to mono-butyl amine was 13.2% andf-to di-butyl amine was 1.69%. The

yields of monoand di-butyl amine were 56.8%

and 7.23%, respectviely. 3

Various modifications are possible within the scope of the invention, and I do not therefore wish to be limited except by the scope of the following claims.

I claim:

1. In the manufacture of mines, the process favoring production of mono-alkyl amines comprising passing a.v compound of the formula ROR', in which It represents an alkyl radical having from one to five carbon atoms and R represents a member. chosen from the group consisting of hydrogen and alkyl radicals hav ing from one to five carbon atoms, together with ammonia through a conduit containing a catalyst consisting of granular alumina coated with a compound chosen from the class consisting of the oxides of chromium, nickel and cobalt.

while heating the mixture to a temperature between the initial reaction tempcrature and the decomposition temperature of the formed amine.

practice of the process was 50.3% mono-butyl 7| 2. In the manufacture of amines, the process favoring production of mono-alkyl amines comprising passing a compound of the formula ROR', in which R represents an alkyl radical having from one to five carbon atoms and R represents a member chosen from the group consisting of hydrogen and alkyl radicals having from one to five carbon atoms, together, with ammonia through a conduit containing granular alumina coated with an oxide of chromium, while'he'ating the mixture to a temperature between the initial reaction temperature and the decomposition temperature of the formed amine.

3. In the manufacture of amines, the process favoring production of mono-alkyl amines comprising passing a compound oi? the formula ROB, in which R represents an alkyl radical having from one to flve carbon atoms and R represents a member chosen from the group consisting of hydrogen and alkyl radicals having from one to five carbon atoms, together with ammonia through a conduit containing granular alumina coated with an oxide of nickel, while heating the mixture to a temperature between the initial reaction temperature and the decomposition temperature of the formed amine.

4. In the manufacture of amines, the process favoring production of mono-alkyl amines comprising passing a compound of the formula ROR',.in which R represents an alkyl radical having from'one to five carbon atoms and R represents a member chosen from the group consisting of hydrogen and alkyl radicals having from one to five carbon atoms, together with ammonia through a conduit containing granular alumina coated with an oxide of cobalt,- while heating the mixture to a temperature between the initial reaction temperature and the decomposition temperature 01 the formed amine.

ROLAND H. GOSI-IORN. 

